PETER PAZMANY CATHOLIC UNIVERSITY Consortium members SEMMELWEIS UNIVERSITY, DIALOG CAMPUS PUBLISHER

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1 PETER PAZMANY CATHOLIC UNIVERSITY SEMMELWEIS UNIVERSITY Development of Complex Curricula for Molecular Bionics and Infobionics Programs within a consortial* framework** Consortium leader PETER PAZMANY CATHOLIC UNIVERSITY Consortium members SEMMELWEIS UNIVERSITY, DIALOG CAMPUS PUBLISHER The Project has been realised with the support of the European Union and has been co-financed by the European Social Fund *** **Molekuláris bionika és Infobionika Szakok tananyagának komplex fejlesztése konzorciumi keretben ***A projekt az Európai Unió támogatásával, az Európai Szociális Alap társfinanszírozásával valósul meg. 9/14/2011. TÁMOP /2/A/KMR

2 Peter Pazmany Catholic University Faculty of Information Technology NEURAL INTERFACES AND PROSTHESES Neurális interfészek és protézisek LECTURE 3 FUNCTIONAL MUSCLE AND NERVE STIMULATION (Funkcionális izom- és idegingerlés) DOMONKOS HORVÁTH, BÁLINT PÉTER KEREKES and GYÖRGY KARMOS

3 FUNCTIONAL ELECTRICAL STIMULATION Definition: functional electrical stimulation is a technique that uses electrical currents to activate nerves innervating extremities affected by paralysis Most common origins of paralysis: Spinal cord injury Head injury Stroke Other neurological disorders Types of paralysis: Paraplegia: both upper or both lower limbs are paralyzed Tetraplegia: all four limbs are paralyzed Hemiplegia: left or right side of the body is paralyzed TÁMOP /2/A/KMR

4 FUNCTIONAL ELECTRICAL STIMULATION (FES) Nerve stimulation: achieved by passing current between two or more electrodes implanted into the body or placed on the skin surface Design: appropriate spatial and temporal patterns of stimulation must be determined in order to produce real functional nerve activation Both nerve responses and stimulus properties must be understood for effective design 9/14/2011 TÁMOP /2/A/KMR

5 PROPERTIES OF ELECTRICAL STIMULATION In FES, stimulation is extracellular, i. e. stimulating electrodes are placed outside the neurons and nerves I 0 : single current point source placed at a distance h from a circular cylindrical fiber 2L: length of fiber a: radius of fiber σ i : intracellular conductivity σ e : extracellular conductivity z: fiber centerline axis Δz: fiber element for numerical calculations 9/14/2011 TÁMOP /2/A/KMR

6 PROPERTIES OF ELECTRICAL STIMULATION The effect of the point source can be described with the following equation: Φ a : extracellular potential field I 0 : current strength σ e : extracellular medium conductivity r: distance from the source to an arbitrary field point Effect of the fiber on the field is ignored. 9/14/2011 TÁMOP /2/A/KMR

7 PROPERTIES OF ELECTRICAL STIMULATION Transmembrane current induced by the stimulation must be equal to the intrinsic ionic current plus the capacitive current of the membrane. This can be fitted into the following equation: r i : intrinsic membrane resistance i m : transmembrane current Φ i : membrane potential z: coordinate along the fiber centerline axis (see Slide 5) See reformatted equation with ionic and capacitive membrane currents on next slide. 9/14/2011 TÁMOP /2/A/KMR

8 PROPERTIES OF ELECTRICAL STIMULATION Replacing Φ i by v m +Φ e and i m by i ion +c m v m / t in the previous equation gives the following: At rest, v m =0 for all z This means: 2 v m / z 2 =0 and i ion =v m /r m As a consequence, the first application of stimulus can be described as follows: 9/14/2011 TÁMOP /2/A/KMR

9 PROPERTIES OF ELECTRICAL STIMULATION According to the previous equation, excitation is possible at the region where 2 Φ e / z 2 is positive because this makes v m / t initially positive. Thus, it is also true conversely that regions where 2 Φ e / z 2 is negative are hyperpolarized because this makes v m / t initially negative. Because of its role in the activation or inhibition of the membrane section, the function 2 Φ e / z 2 is called the activating function 9/14/2011 TÁMOP /2/A/KMR

10 PROPERTIES OF ELECTRICAL STIMULATION Time evolution of induced transmembrane voltage along a fiber. Different curves represent different stimulus durations in milliseconds. Fiber structure is shown on Slide 5, h=0.02 cm. 9/14/2011 TÁMOP /2/A/KMR

11 PROPERTIES OF ELECTRICAL STIMULATION Conclusion: a space clamped membrane patch and a whole fiber react differently on different durations of an external point stimulus Space clamped membrane patch: threshold potential relatively independent of stimulus duration Whole fiber: higher threshold for shorter stimulus duration. This effect is stronger when the source is close and weakens when the source is move further from the fiber. These effects result from the hyperpolarized regions flanking the depolarized region. The flanking hyperpolarized regions can block action potential generation along the fiber. 9/14/2011 TÁMOP /2/A/KMR

12 TYPES OF ELECTRICAL NERVE STIMULATION 9/14/2011 TÁMOP /2/A/KMR

13 EFFECTS OF ELECTRICAL STIMULATION Current-force relation at nerve stimulation 9/14/2011 TÁMOP /2/A/KMR

14 EFFECTS OF ELECTRICAL STIMULATION Current-force relation at muscle stimulation 9/14/2011 TÁMOP /2/A/KMR

15 EFFECTS OF ELECTRICAL STIMULATION Charge production threshold for nerves and muscles: threshold is much lower in nerves than in muscles 9/14/2011 TÁMOP /2/A/KMR

16 EFFECTS OF ELECTRICAL STIMULATION Functional Electrical Stimulation: A Practical Clinical Guide (2nd Edition). Benton, Baker et al., 1981 Representation of current density at nerve stimulation 9/14/2011 TÁMOP /2/A/KMR

17 EFFECTS OF ELECTRICAL STIMULATION Functional Electrical Stimulation: A Practical Clinical Guide (2nd Edition). Benton, Baker et al., 1981 Effect of stimulus frequency on fatigue 9/14/2011 TÁMOP /2/A/KMR

18 STIMULUS WAVEFORMS Monophasic The monophasic waveforms tend to be asymmetric biphasic as the net charge built up in the body by the waveform discharges Biphasic charge balanced 9/14/2011 TÁMOP /2/A/KMR

19 UPPER LIMB FES SYSTEMS Schematic of a typical upper limb FES system 9/14/2011 TÁMOP /2/A/KMR

20 UPPER LIMB FES SYSTEMS Different electrodes typically used in upper limb FES systems Sixteen channel implantable stimulator developed for upper and lower limb FES systems 9/14/2011 TÁMOP /2/A/KMR

21 Developed at Case Western Reserve University, Cleveland, Ohio in 1986 Given FDA approval for general use in 1997 System overview: NEURAL INTERFACES AND PROSTHESES FREEHAND SYSTEM Shoulder position sensor implanted into non-injured shoulder External control unit: receives shoulder position information and computes stimulation pattern based on it. Implanted stimulator: receives stimulation pattern from external controller via a transmitting coil and stimulates implanted electrodes via electrode leads Electrodes: implanted into arm and wrist muscles to stimulate them according to the pattern received from the stimulator Programmable to six different movements, including palmar and lateral grasp 9/14/2011 TÁMOP /2/A/KMR

22 FREEHAND SYSTEM Schematic of Freehand system components 9/14/2011 TÁMOP /2/A/KMR

23 FREEHAND SYSTEM X-ray pictures showing implanted Freehand system components 9/14/2011 TÁMOP /2/A/KMR

24 FREEHAND SYSTEM IN USE Patient applying make up with help of her implanted Freehand system 9/14/2011 TÁMOP /2/A/KMR

25 Developed by NESS Ltd., Israel in 2004 Originally called Handmaster NEURAL INTERFACES AND PROSTHESES NESS H200 SYSTEM Non-invasive prosthesis: no implanting operation needed Two parts: orthosis and microprocessor Orthosis: external stimulating device applied on forearm and wrist Stimulates four different muscles in forearm wrist through the skin Microprocessor: computes stimulation patterns for different tasks 9/14/2011 TÁMOP /2/A/KMR

26 NESS H200 SYSTEM Orthosis Microprocessor Patient using her NESS H200 system 9/14/2011 TÁMOP /2/A/KMR

27 Developed at the University of Alberta in 1996 Non-invasive device For patients with intact wrist moving capabilities Electrodes placed on skin over wrist NEURAL INTERFACES AND PROSTHESES BIONIC GLOVE Sensor records wrist movements, transmits the data to the microprocessor Microprocessor computes finger stimulation patterns based on wrist movement data Stimulator stimulates electrodes placed over wrist The whole system can be worn on a glove on wrist 9/14/2011 TÁMOP /2/A/KMR

28 BIONIC GLOVE Patient using his Bionic Glove 9/14/2011 TÁMOP /2/A/KMR

29 BELGRADE GRASPING SYSTEM Developed at the Belgrade University in 2001 Not only wrist and forearm but also elbow stimulation Non-invasive, uses skin surface electrodes Patient using Belgrade Grasping System (left) and electrode placement for grasping function (right) 9/14/2011 TÁMOP /2/A/KMR

30 Developed at the Technical University of Zurich in 2000 Restores hand grasping function NEURAL INTERFACES AND PROSTHESES ETHZ-PARACARE NEUROPROSTHESIS Patient controls the external control unit by hand ETHZ-Paracare system components (left) and Patient using ETHZ-Paracare system for grasping (right) 9/14/2011 TÁMOP /2/A/KMR

31 BION MICROSTIMULATOR Developed by Advanced Bionics Corporation in 2005 Implantable, battery powered microstimulator Small enough to be able to be implanted into a muscle or near a nerve Recharging and communication through a magnetic transmission coil Several different uses: chronic pain, bladder function restoration, shoulder subluxation treatment Demonstrating the size of a BION microstimulator 9/14/2011 TÁMOP /2/A/KMR

32 BION MICROSTIMULATOR Block diagram of BION 1, the first version of BION stimulators The latest version of BION stimulators 9/14/2011 TÁMOP /2/A/KMR

33 BION MICROSTIMULATOR FOR SHOULDER SUBLUXATION TREATMENT Shoulder subluxation: paralyzed shoulder joint (for example in stroke survivors) lets the humerus to leave the cotyle of shoulder which causes pain Stimulation of shoulder joint keeps humerus in the cotyle and reduces pain BION stimulator implanted into shoulder to provide stimulation 6 hours/day stimulation Shoulder subluxation treatment (top) and electrode position in shoulder (bottom) 9/14/2011 TÁMOP /2/A/KMR

34 Developed at the Rehabilitation Institute of Chicago in 2006 Full arm prosthesis for upper limb amputees Prosthesis attached to the shoulder NEURAL INTERFACES AND PROSTHESES BIONIC ARM Loose ends of arm motor and sensory nerves re-innervated into chest using technique called targeted re-innervating Smarter control of prosthetic arm possible with regaining sense of touch: prosthetic arm moved with the movement of chest muscles and arm sensory nerves re-innervated into chest sensory nerves Two veterans already use the system 9/14/2011 TÁMOP /2/A/KMR

35 BIONIC ARM Schematic of targeted motoric reinnervation (top) and targeted sensory re-innervation (bottom) Kuiken, TA; Miller, LA ; Lipschutz, RD ; Lock, BA; Stubblefield, K; Marasco, PD; Zhou, P; Dumanian, GA; Targeted reinnervation for enhanced prosthetic arm function in a woman with a proximal amputation: a case study, LANCET, 369 (9559): FEB /14/2011 TÁMOP /2/A/KMR

36 BIONIC ARM Maps of surface electromyogram amplitude for four different movements Kuiken, TA; Miller, LA ; Lipschutz, RD ; Lock, BA; Stubblefield, K; Marasco, PD; Zhou, P; Dumanian, GA; Targeted reinnervation for enhanced prosthetic arm function in a woman with a proximal amputation: a case study, LANCET, 369 (9559): FEB /14/2011 TÁMOP /2/A/KMR

37 BIONIC ARM Patients wearing their Bionic Arm prosthesis 9/14/2011 TÁMOP /2/A/KMR

38 CYBERHAND PROJECT European research project with institutions from Italy, Spain, Germany, Denmark Led by Scuola Superiore Sant Anna, Pontedera, Italy Aims to develop a complex system implementing several functions: Efferent and afferent regeneration-type electrodes Implantable system for neural stimulation and recording Efferent and afferent telemetric links "Biologically-inspired" mechatronic hand Biomimetic sensors External unit for decoding patient's intentions and for prosthesis control System to deliver the cognitive feedback to the patient 9/14/2011 TÁMOP /2/A/KMR

39 CYBERHAND PROJECT Prototype of CyberHand (left) and illustrations of implemented functions (right) 9/14/2011 TÁMOP /2/A/KMR

40 I-LIMB HAND Developed by Touch Bionics Inc. in 2008 Uses myoelectric signals recorded from skin surface to control hand and fingers First upper limb prosthesis that has five individually powered fingers Implements four different grip patterns and two grasps Has different colour skin-like coverings 9/14/2011 TÁMOP /2/A/KMR

41 STIMUSTEP IMPLANTED DROPPED FOOT STIMULATOR Strains the flexor muscles of the ankle when the foot is not on the floor. Developed by the University of Twente and Roessingh Research. & Development in Holland in collaboration with the UK based company, Finetech-Medical Ltd. 9/14/2011 TÁMOP /2/A/KMR

42 FUNCTIONAL ELECTRIC STIMULATION OF A PARAPLEG PATIENT 8 channel stimulation pattern making for every individual person changeable parameters: Frequency: 1-200Hz (1Hz step) Current: 0-130mA (1mA step) Impulse width: 10us-1ms Impulse type: unipolar bipolar Data gathering to SD card NEURAL INTERFACES AND PROSTHESES 9/14/2011 TÁMOP /2/A/KMR

43 FES CYCLING 9/14/2011 TÁMOP /2/A/KMR

44 FES CYCLING Muscle contraction is an electrochemical process that is stimulated by an electric current and propagated through nerve and muscle cells. When an electrical potential is applied between two electrodes placed on the surface of the body electric current passes from one electrode to the other through the tissue. If the tissues contain any muscles they will contract during the passage of the electricity and relax when it stops. By controlling the timing of the electrical impulses and the positioning of the electrodes it is possible to create various patterns of muscle contraction and relaxations that can enable a paralysed limb to perform a function. 9/14/2011 TÁMOP /2/A/KMR

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47 WALKING MOBILITY SYSTEM Implantable Reciever Stimulator External Control Unit Clinical Interface Target Muscles: Vastus lateralis Gluteus Maximus Semimembranosus Erector Spinae Tibialis Anterior Iliopsoas Sartorius TFL 9/14/2011 TÁMOP /2/A/KMR

48 IMPLANTED PATIENTS 9/14/2011 TÁMOP /2/A/KMR

49 SWISS FEDERAL INSTITUTE OF TECHNOLOGY Dept. of Information Technology and Electrical Engineering FES Roller 9/14/2011 TÁMOP /2/A/KMR

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51 ERIGO TILT TABLE WITH INTEGRATED ROBOTIC STEPPING SYSTEM Movement therapy and loading of the legs are important elements in the rehabilitation of bed-ridden neurological patients. The development of a tilt table with an integrated stepping system provides physicians and therapists with the opportunity to do intensive movement therapy of legs combined with verticalization. Accordingly, the Erigo allows two approved forms of therapy to be accomplished at the same time. The Erigo therefore supports and facilitates the mobilization of bed-ridden patients. 9/14/2011 TÁMOP /2/A/KMR

52 Rehabilitation technique, to fortificate the muscles using the whole body. 9/14/2011 TÁMOP /2/A/KMR

53 LOKOMAT BODY WEIGHT SUPPORTED TREADMILL TRAINING The Lokolift is an electronically controlled body weight support system for treadmill training that allows a constant and precise body weight support. The user-friendly patient handling through the user interface allows the therapist to change the weight support of the patient without having to stop the training. Based on a closed loop control, the weight support is measured exactly, registered by the computer and sent to the drives for the adjustment of the weight support. The integrated drives provide a low-inertia movement and allow a physiological gait that supports a successful rehabilitation process. 9/14/2011 TÁMOP /2/A/KMR

54 FUTURE DIRECTIONS LOWER EXTREMITY SYSTEMS Ambulation Closed loop control for balance and posture New fundamental aproaches to interfacing with the nervous system Incomplete spinal cord injury for ambulation Combination therapies 9/14/2011 TÁMOP /2/A/KMR

55 REQUIREMENTS OF A PRACTICAL FES SYSTEM (electrical orthosis) 1. Should be Simple to put on and put off (Don and Doff) This is vital as it will to a large extent determine the amount of use and how much the patient will get out of their system. This will limit the number of connections and leads that are external to the body. 2. Function must be Relevant to the User Some functions seem to have 'obvious' relevance to anyone. But even a function like standing may be of very little use to paraplegic in adapted accommodation. 3. System must Consistently Provide the Desired Function The electrical orthosis must provide the desired function under a range of working conditions both external, e.g. location, and internal, e.g. electrode positioning. 9/14/2011 TÁMOP /2/A/KMR

56 4. The System must include the User The condition of the user's muscles, bones, ligaments and cardiovascular performance are of vital importance in ensuring that the required function can be attained safely and repeatably. 5. User must be Aware of the Limitations of the System It must be ensured that the user has realistic expectations. With open-loop systems the user should understand the problems that may occur, eg with fatigue, and realise how these will affect the performance of the system. 6. User must Understand Committment Required to Maximise the Benefits Generally a long term commitment to a training program (>3 months for "sit to stand") is required. 7. System should Ideally be Fail Safe At present this is not always possible, e.g. how does one make an electrical stimulation only standing system fail safe! With open-loop systems the user should possess the strength/control to cope in the event of a systems failure. The degree to which failure is dangerous depends on the system - but the possibility of failure needs to be carefully considered in programming the stimulator. 9/14/2011 TÁMOP /2/A/KMR

57 A practical electrical orthosis consists of two components. First, a reliable and adaptable system capable of responding to changing parameters. Second, a trained user with the necessary motivation. Both parts are of equal importance! 9/14/2011 TÁMOP /2/A/KMR

58 BOVEL CONTROL Annual and cumulative costs of bladder and bowel care after spinal cord injury are reduced after combined sacral dorsal root rhizotomy and implantation of a sacral anterior root stimulator for bladder emptying. Cumulative costs of bladder and bowel care after spinal cord injury: comparison of traditional and electrical stimulation treatment. Jezernik et al., Neurological Research, 2002, 24: /14/2011 TÁMOP /2/A/KMR

59 BLADDER INNERVATION Systems Spinal segment Periferial descending Stimulus effect Parasympatic S2 - S4 Nervus pelvicus Sympatic Th11 - L2 Nervus hypogastricus Bladder depleteing muscle contraction. Inner sphincter yielding (the bladder deplete). Bladder depleteing muscle yields. Urethra contraction. Inhibition of the parasimpatic ganglions (retention) Motoric S3 - S4 Nervus pudendalis Urethra spinchter contraction. 9/14/2011 TÁMOP /2/A/KMR

60 When the thoracic spinal cord is injured (crosswise lesion), first complete retention, and then automatical bladder develops: there is no involuntary bladder, but the bladder automatically eliminated, if it reaches a limit, but the excretion is not perfect. If the sacral spinal cord (S2-S4) is damaged, the wall of the bladder becomes atonical, therefore a widening of the bladder and urinary retention develops, with incontinence (autonomous bladder). If the sensory part of the sacral reflex arc is damaged, then the need of urination and the bladder reflex ceases. The bladder saturates and incontinence (ischuria paradoxa) develops. 9/14/2011 TÁMOP /2/A/KMR

61 Reflex incontinence: complete spinal cord lesion, there is no sensory stimulus Pressure incontinence: Detrusor instability, Stress incontinence: pl. effect of cough onset of urination Sacral anterior root stimulation (SARS): thick fibers to the bladder sphincter, thin preganglionar parasympathetic fibers to the bladder. Solution: repetitiv short stimulus series Extradural stimulation: mostly after posterior root cutoff Neuromodulation: (Medtronic Interstim) 9/14/2011 TÁMOP /2/A/KMR

62 REGULATE THE BLADDER OPERATION OF INTERVENTION Bladder innervation, posterior rhizotomy site (transection of sacral dorsal roots to abolish bladder hyper-reflexia and detrusor sphincter dyssynergia), and location of extradural electrodes for sacral anterior root stimulation to produce bladder contractions and bladder emptying. 9/14/2011 TÁMOP /2/A/KMR

63 Spinal reflex pathways controlling the lower urinary tract. NEURAL INTERFACES AND PROSTHESES THE SPINAL REFLEX INFLUENCE WITH THE ELECTRICAL STIMULATION OF N. PUDENDALIS Electrical stimulation of large pudendal afferents inhibits parasympathetic activity to the bladder. Such stimulation can be achieved by implanted electrodes (sacral afferent stimulation) or by transcutaneous electrical stimulation (anal and vaginal plug electrodes, dorsal penile or clitorial electrodes). Jezernik et al., Neurological Research, 2002, 24: /14/2011 TÁMOP /2/A/KMR

64 REDUCED BLADDER CAPACITY DEMONSTRATED IN A CONTROL CYSTOMETROGRAM (CMG) OF A SPINAL CORD INJURED PERSON Jezernik et al., Neurological Research, 2002, 24: /14/2011 TÁMOP /2/A/KMR

65 REDUCED BLADDER CAPACITY DEMONSTRATED IN A CONTROL CYSTOMETROGRAM (CMG) OF A SPINAL CORD INJURED PERSON A: Control, B: Increase in the bladder volume during a cystometry performed during a continuously applied electrical stimulation (15 Hz stimulation frequency, 200 μsec pulse width). C: Mean change in the bladder capacity obtained during a series of cystometries. Cystometrograms that were measured with neuromodulation switched on are indicated in the middle of the graph. The carry-over effects of neuromodulation can be observed. 9/14/2011 TÁMOP /2/A/KMR

66 SCHEMATICS SHOWING THE PRINCIPLE FOR CONDITIONAL NEUROMODULATION Jezernik et al., Neurological Research, 2002, 24: /14/2011 TÁMOP /2/A/KMR

67 SCHEMATICS SHOWING THE PRINCIPLE FOR CONDITIONAL NEUROMODULATION A: Bladder pressure is sensed and the bladder pressure signal used to detect bladder contractions and to trigger pudendal afferent stimulation via dorsal penile electrodes only when needed, i.e. if there is no contraction there is no need for stimulation. B: Top panel shows a cystometrogram without neuromodulation, and the bottom panel shows a cystometrogram during a conditional neuromodulation (switched on/off based on the bladder pressure signal). Urine leakage occurred at a higher bladder volume when the conditional neuromodulation was applied. 9/14/2011 TÁMOP /2/A/KMR

68 Near the cathode both small and large fibers are excited to produce action potentials (APs) which will propagate along the fibers. Near the anode the fiber membranes are hyperpolarized. If sufficiently hyperpolarized, an AP cannot pass the hyperpolarized zone, i.e. the fiber is blocked. Large fibers can be blocked at lower currents than required to block the smaller ones, which enables a selective fiber blockage. NEURAL INTERFACES AND PROSTHESES PRINCIPLE OF SELECTIVE SMALL FIBER ACTIVATION Jezernik et al., Neurological Research, 2002, 24: /14/2011 TÁMOP /2/A/KMR

69 SPINAL CORD STIMULATION RESEARCH METHOD 9/14/2011 TÁMOP /2/A/KMR

70 MULTICONTACT ELECTRODE FOR SACRAL SPINAL CORD STIMULATION 9/14/2011 TÁMOP /2/A/KMR

71 CAT BEFORE AND AFTER SPINAL CORD CUTOFF 9/14/2011 TÁMOP /2/A/KMR

72 STIMULATION INDUCED URINATION IN ALERT CATS WITH SPINAL CORD CUTOFF 9/14/2011 TÁMOP /2/A/KMR

73 Neuroprosthesis for afferent nervous activity Jezernik et al., Neurological Research, 2002, 24: /14/2011 TÁMOP /2/A/KMR

74 NEUROPROSTHESIS FOR AFFERENT NERVOUS ACTIVITY A: A neural prosthesis that would detect overactive bladder contractions by recording and processing of the bladder afferent nerve traffic, and that would after detection inhibit the bladder and prevent high bladder pressures. The latter could be achieved by conditional stimulation of the bladder inhibitory nerves. B: Actual bladder afferent nerve signal (top panel) recorded during three bladder contractions (corresponding bladder pressure is shown in the bottom panel). Bladder contractions can be detected from the increases in the ENG signal 9/14/2011 TÁMOP /2/A/KMR

75 The Finetech Medical VOCARE Bladder System consists of the following subsystems: The Implanted Components include the Implantable Receiver-Stimulator and Extradural Electrodes. The External Components include the External Controller, External Transmitter, External Cable, Transmitter Tester, Battery Charger and Power Cord. The Surgical Components include the Surgical Stimulator, Intradural Surgical Probe, Extradural Surgical Probe, Electrode Test Cable, and Silicone Adhesive 9/14/2011 TÁMOP /2/A/KMR

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77 The INTERSTIM BLADDER SYSTEM is a radiofrequency powered motor control neuroprosthesis, which consists of both implanted and external components. The VOCARE BLADDER SYSTEM delivers low levels of electrical stimulation to a spinal cord injured patient's intact sacral spinal nerve roots in order to elicit functional contraction of the muscles innervated by them. 9/14/2011 TÁMOP /2/A/KMR

78 MEDTRONIC INTERSTIM SYSTEM Procedure and location of the permanent wire electrode placement for the Medtronic Interstim system. The electrode is usually placed into the sacral foramina S3. www. medtronic.com 9/14/2011 TÁMOP /2/A/KMR

79 REFERENCES AND FURTHER READING Benton L. A., Baker L. L., Bowman B. R., Waters R. L., Functional Electrical Stimulation: A Practical Clinical Guide (2nd Edition), Rancho Rehabilitation Engineering Program. Rancho Los Amigos Medical Centre, Chapin J. K., Moxon K. A. (eds.), Neural Prostheses for Restoration of Sensory and Motor Function, CRC Press, Zhou D., Greenbaum E. (eds.), Implantable Neural Prostheses 1 Devices and Applications, Springer, pdf 9/14/2011 TÁMOP /2/A/KMR

80 REVIEW QUESTIONS What is functional electrical stimulation (FES)? What are the most common origins of paralysis? For which stimulation is charge production threshold higher: nerve or muscle stimulation? What is the effect of stimulus frequency on fatigue? List and characterize three upper limb FES systems! List and characterize three lower limb FES systems! What is body weight supported treadmill training? What are the requirements of a practical FES system? How do FES systems for bladder function restoration work? 9/14/2011 TÁMOP /2/A/KMR